In linear guide apparatuses, generally, a slider is typically provided with a lubricant, such as grease, filled therein to lubricate rolling elements and the raceway surface for the rolling elements. As the slider travels, the lubricant inside the slider is transferred by the rolling elements onto a guide rail to be discharged to the outside of the slider. Thus, addition of the lubricant is demanded to the inside of the slider through regular maintenance.
In general, linear guide apparatuses include seals for sealing openings at gaps between the guide rail and the slider to thereby prevent the lubricant in the slider from leaking to the outside and prevent external foreign substances from entering the slider. To describe in detail, the slider includes side seals for sealing openings at axial end faces of the slider and an under seal for sealing an opening at the underside of the slider. These openings are parts of the openings at the gaps between the guide rail and the slider, and the side seals and the under seal are designed to seal the entirety of the openings.
With all the openings sealed as described above, however, the lubricant in the slider still leaks to the outside in some cases. For example, a gap may be generated at a seam between a side seal and the under seal due to the shape accuracy of the seals, misalignment in the position of a seal in association with the travel of the slider, and other reasons. The lubricant may leak through this gap.
A technique is disclosed in PLT 1 for preventing the lubricant from leaking through such a gap generated at a seam between seals. In the technique in PLT 1, plural seals typically provided in a linear guide apparatus are integrated into an endless seal. This endless seal provides a seal around the rolling elements, thereby providing a structure with no seal seam and thus the leak of the lubricant hardly occurs.